Associations between infant brain structure and function assessed using magnetic resonance imaging and...

Negative affectivity (NA), the tendency to experience negative emotions, is a robust predictor of later psychiatric disorders. Infancy is a period marked by rapid maturation in emotional functioning as well as brain structure and function. Thus, characterizing associations between brain structure and function and NA could yield important insights into the etiology of mental health difficulties. This narrative review synthesizes findings on associations between brain structure and function assessed using magnetic resonance imaging (MRI) and parent-reported NA in the first two years of life. Three key takeaways emerged. First, amygdala volume and white matter integrity was negatively associated with NA. Amygdala functional connectivity was also found to be associated with NA, though the direction of associations varied by networks examined. Second, associations between default mode (DMN) intra- and inter-network connectivity and NA varied based on the specific networks examined and developmental timepoint of assessment. Third, orbitofrontal cortex (OFC) functional connectivity and perfusion were negatively associated with NA, while medial and lateral OFC white matter integrity were predominantly positively associated with NA. Most reported associations had small effect sizes. Further, small sample size for most studies, and heterogeneity in both the MRI data processing and analyses, limit confidence in the results. Future research would benefit from robust infant MRI processing pipelines, larger collaborative datasets, extended longitudinal designs beyond 12 months, examination of genetic and prenatal factors influencing regional brain and emotional development, comprehensive statistical reporting, and integrating parent-report and observational temperament measures to better characterize early neurodevelopmental pathways to psychopathology risk.